Mowing attachments having articulated booms are well known in the art. These mower attachments or units are used to facilitate cutting of grass, weeds and brush on shoulders, sidehills, berms, and the like at a position remote from the path of travel of the tractor on which the unit is carried. For example, U.S. Pat. No. 3,624,698 teaches a cutter or mower unit carried on an articulated arm for lateral and vertical movement relative to the tractor, as well as for pivotal movement about a vertical axis. The articulated arm is actuated by a plurality of hydraulic cylinders that are selectively operated to move the mower unit to a desired mowing position or transport position. The articulated boom assembly described in U.S. Pat. No. 4,502,269, is also moved by a plurality of hydraulic cylinders to adjust the position of the mower unit relative to the tractor.
The present invention provides an improved articulated boom which is actuated by a single linearly movable power unit and movable from a mowing position either manually, or as a result of striking an obstruction, to a transport position. The boom structure is movable to folded and unfolded positions therefor so as to retain the mower unit against being lifted substantially above the ground whereby to limit the risk of injury due to exposure of the mower unit cutting blades.